I'm trying to record vocals but they come out super quiet even when I have gain turned up and everything...is there a way to increase my input volume???

The record level is set with the audio interface not MC7. MC7 gain and volume only affect playback.

How do you have the microphone connected?  Are you using an audio interface with a preamp?  is your microphone connected (to what) using the 1/4 inch jack or an XLR (three pronged) cable into your audio interface? 

Does your microphone have a 10Db pad on it?
 
Glen
 
BTW - Welcome to the forum.

Right click on the speaker icon located in the taskbar on the bottom right of your screen or go to Control Panel > Hardware and Sound > Sound > Manage Audio Devices and select the recording tab.
 
Right click on your audio device, select Properties, then Levels to set your audio device recording volume level.  As others have indicated your audio device and Windows are responsible to get sound to the input of a Music Creator track.
 
Once you are sure you have audio going to a track, click on the track to make it the active track.  That track will now be available in the Track Inspector view (far left of your screen).  Click on Properties at the bottom of the Track Inspector and place a checkmark against Input/Trim.  Now you will be able to slightly adjust the incoming audio for the track.

Yep... many of the interfaces have control panel software where you set the input levels.
 
Also, be sure the preamps are present in the interface and turned on, and if it's a condenser mic, be sure the phantom power is on.
 
Some interfaces do not have pre's in them but most do.
 
More then likely it's the settings.